But he who neither thinks for himself nor learns from others, is a failure as a man.

The fool learns by suffering.

The potter is at enmity with the potter.

He's only harming himself who's bent upon harming another

Often even a whole city suffers for a bad man who sins and contrives presumptuous deeds.

Before the gates of excellence the high gods have placed sweat; long is the road thereto and rough and steep at first; but when the heights are reached, then there is ease, though grievously hard in the winning.

Invite your friend to dinner; have nothing to do with your enemy.